Nancy Newton Verrier, Ph.D.'s The Primal Wound, sources the difficulties to the separation of the newborn from the mother. "I believe that the connection established during the nine months in utero is a profound connection, and it is my hypothesis that the severing of that connection in the original separation of the adopted child from the birth mother causes a primal or narcissistic wound, which affects the adoptee's sense of Self and often manifests in a sense of loss, basic mistrust, anxiety and depression, emotional and/or behavioral problems, and difficulties in relationships with significant others (21)." Verrier has been criticized for her work, but her response says it all, "The only people who can really judge this work, however, are those about whom it is written: the adoptees themselves. Only they, as they note their responses to what is written here, will really know in their deepest selves the validity of this work, the existence or nonexistence of the primal wound" (xvii). (from https://www.adoptionhealing.com/ginni.html)